This application claims priority of the German patent application 101 15 066.0 filed Mar. 27, 2001 which is incorporated by reference herein.
The invention concerns an apparatus for drying solvent-based ink, in particular of imprinted plastic cassettes for histological preparations and/or of imprinted glass specimen slides for microscopic thin sections.
For the microscopic observation of preparations, in particular histological preparations, the latter must first be subjected to a chemical treatment in which the water contained in the specimen is removed and is replaced, for example, by paraffin or another medium. For this chemical treatment, the specimens are introduced into plastic cassettes. A cassette of this kind is depicted and described in, for example, U.S. Pat. No. 5,821,115 A.
Formulas for this kind of specimen treatment are known, for example, from the document xe2x80x9cEmbedding and sectioning methods for microscopic preparations [Einbettung-und Schneideverfahren fxc3xcr mikroskopische Prxc3xa4parate], Ernst Leitz GmbH, Liste 530-18a, September 1973.xe2x80x9d The preparation methods described are characterized in that water is removed from the preparation with ethanol/ethyl ether/propanol, and the preparation is then embedded in paraffin/methacrylate. It is understood that the plastic cassettes and the materials that are used must not react with the chemical reagents.
In this treatment, the specimens are stabilized to the extent that by means of a microtome, thin sections of the specimens can be made and can then each be mounted onto a glass specimen slide. Depending on the examination method, several thin sections are made of each preparation and are mounted onto the specimen slides. Prior to the actual microscopic observation, the preparations mounted onto the specimen slides must also be stained. It is usual in this context that not all preparations go through the same staining process, but instead that depending on the examination method, three or more differently stained preparations are produced.
For differentiation and identification, the individual cassettes and specimen slides must be given a label or code. It was hitherto usual to label the cassettes and specimen slides manually in pencil. Graphite was the only medium that was resistant to the reagents of the embedding process, but with the disadvantage that it cannot be applied in smudgeproof fashion. With manual labeling of the cassettes and/or specimen slides, however, errors can occur which then result in medical misdiagnoses.
For this reason, computer-assisted labeling systems have been developed which have largely eliminated these manual labeling errors. The difficulty that exists with these labeling systems is that of finding a suitable printing or writing medium. This medium must be characterized in that it resists a wide variety of chemical solvents and reagents, and adheres securely both to the plastic cassettes and to the glass of the specimen slide or the coated portion of the specimen slide. In addition, there is very little room on the cassettes and specimen slides for a corresponding code, so that the code or label must be applied in correspondingly delicate fashion.
GB Patent 2 206 083 discloses an xe2x80x9cengraving machinexe2x80x9d for a specimen slide and/or a cassette. This engraving device is controlled via a computer and an interface, and allows corresponding markings to be scratched into the cassette or specimen slide. It is disadvantageous, however, that this machine is very loud and very slow in operation, and also produces a great deal of debris due to the engraving. The engraved code is moreover very difficult to read.
GB Patent 2 235 163 A discloses a plotter for plastic cassettes in which labeling is performed with a thermal method using a heatable plotter pin and a carbon ribbon. The disadvantage here is that this method can be applied only to plastic, and moreover that only low resolution and a low printing speed can be achieved. The low printing speed results from the fact that the pin must move to each letter individually in the manner of a plotter.
In all known printing systems the resolution is relatively poor, so that only a very xe2x80x9ccoarsexe2x80x9d label can be applied. It is thus not possible to realize the applied code in machine-readable fashion. The application of very thin lines, such as is necessary e.g. for barcodes, is not feasible with any of the known printing devices.
It is therefore the object of the present invention to optimize the drying process.
An optimum printing result can be achieved only with an inkjet printer and a special ink. A printing system of this kind is depicted and described in the present Application.
This printing system is characterized in that for printing with a piezoelectric printing head, a solvent-based ink comprising a carbon black pigment is used. The carbon black pigment also ensures that a printed barcode exhibits very high contrast.
At room temperature, the applied ink requires approximately 20 seconds until the solvent has evaporated. The ink is then xe2x80x9cdry to the touchxe2x80x9d and resistant to unintentional smudging. At this stage, however, the ink is not yet resistant to the chemicals of the chemical processes already described. Complete drying of the ink requires a very long period of time.
The apparatus for drying solvent-based ink, in particular of imprinted plastic cassettes for histological preparations and/or of imprinted glass specimen slides for microscopic thin sections, is characterized in that the apparatus comprises a hot-air blower and/or a flash device for drying the ink. The result is that the solvent can evaporate very quickly, and the drying process is thus considerably accelerated. It has proven to be advantageous if the ink, after a pre-drying operation by means of the hot-air blower, is completely dried with the considerably greater energy of a flash lamp. The ink is optimally xe2x80x9ccuredxe2x80x9d because of the high IR and UV energy component of the flash light. Optimum xe2x80x9ccuringxe2x80x9d can only occur, however, if the ink is already dry to the touch, since otherwise the abrupt evaporation of the solvent causes carbon black pigment to be carried off and deposited as a coating on the flash tube and elsewhere. In addition, an increased flash energy consumption is required for the evaporation process.
In a further embodiment of the invention, the flash device comprises a flash tube of U-shaped configuration and a reflector of curved configuration. The radius of the reflector is adapted to the geometrical arrangement and the dimensions of the two limbs of the flash tube. The flash light is thereby reflected to a focal point.
In a further embodiment of the invention, a holding apparatus for the specimen slide and/or cassette is provided in the vicinity of said focal point, so that both the specimen slide and the cassette are held in an optimized position for flash illumination. Also present in this position is a cover apparatus that protects the unimprinted portion of the specimen slide and/or cassette from the flash light. This is advantageous in particular if the cassette or specimen slide already has a preparation in place, and if the latter might be damaged by the high energy of the flash light.
In a further embodiment of the invention, the flash device is equipped with a movable closure. By way of this closure, the specimen slides and/or cassettes can be removed from the flash device and transported to a removal device (not depicted). During the flashing operation, the interior of the flash device is sealed in light-tight fashion.
The invention is also characterized in that the flash device comprises a fan for transporting off the hot air produced in the flash region.
In a further embodiment of the invention, the hot-air blower comprises a heater, a fan, and a hot-air conduit. The hot air is directed through the hot-air conduit onto the cassette and/or specimen slide to pre-dry the ink. It has proven to be advantageous if the fan of the hot-air blower is joined via a conduit system to the flash device, so that the fan draws in air that has already been preheated.
In a further embodiment of the invention, a control device which controls the temperature of the flow of hot air is associated with the hot-air blower. In the context of biological preparations in particular, the flow of hot air on the cassette and/or specimen slide is limited by the control device to 45xc2x0 C.
In a preferred embodiment of the invention, provision is made for the imprinted plastic cassette and/or imprinted glass specimen slide to be exposed for approximately two seconds to the flow of hot air from the hot-air blower so that the ink is pre-dried, and for the imprinted plastic cassette and/or imprinted glass specimen slide then to be exposed to the light of a xenon flash tube so that the ink is completely dried.
In a further embodiment of the invention, multiple cassettes and/or multiple specimen slides can also be processed concurrently with one another, and the respective ink dried. Mixed operation is also possible.